Quran

 59:14

لَا يُقَاتِلُونَكُمْ جَمِيعًا إِلَّا فِي قُرًى مُحَصَّنَةٍ أَوْ مِنْ وَرَاءِ جُدُرٍ ۚ بَأْسُهُمْ بَيْنَهُمْ شَدِيدٌ ۚ تَحْسَبُهُمْ جَمِيعًا وَقُلُوبُهُمْ شَتَّىٰ ۚ ذَٰلِكَ بِأَنَّهُمْ قَوْمٌ لَا يَعْقِلُونَ ﴿١٤﴾

14. They will not fight you all together, except from fortified strongholds, or from behind walls. Their hostility towards each other is severe. You think they are united, but their hearts are divided. That is because they are a people who do not reason.